Thanks for your comment on the filament holder.
It's a great tip you give to slightly change the angle so the filament can run through the holder with less friction, but there is also something else to concider.
The way the holder is designed at this moment, the input of the filament through the printer has a little hang over the filament spool. I do this because before I did this, sometimes the filament fell of the spool, causing it to get stuck and make the printer stop feeding the filament. With the little overhang, this problem was solved.
As for the more abressive filaments, like neon glow, metal partical filaments and even woodfill, they tear down the spoolholder as much as they do with your nozzle. I have no problem redesigning the filament holder to better accept the use of this kind of filament, but it will be a redesign of the original holder then.
This week I am very busy, but next week I will see if I can make a redesign.